Visualizing the kinetic power stroke that drives proton-coupled zinc(ii) transport

Sayan Gupta, Jin Chai, Jie Cheng, Rhijuta D'Mello, Mark R. Chance, Dax Fu

Research output: Contribution to journalArticle

Abstract

The proton gradient is a principal energy source for respiration-dependent active transport, but the structural mechanisms of proton-coupled transport processes are poorly understood. YiiP is a proton-coupled zinc transporter found in the cytoplasmic membrane of Escherichia coli. Its transport site receives protons from water molecules that gain access to its hydrophobic environment and transduces the energy of an inward proton gradient to drive Zn(ii) efflux. This membrane protein is a well-characterized member of the family of cation diffusion facilitators that occurs at all phylogenetic levels. Here we show, using X-ray-mediated hydroxyl radical labelling of YiiP and mass spectrometry, that Zn(ii) binding triggers a highly localized, all-or-nothing change of water accessibility to the transport site and an adjacent hydrophobic gate. Millisecond time-resolved dynamics reveal a concerted and reciprocal pattern of accessibility changes along a transmembrane helix, suggesting a rigid-body helical re-orientation linked to Zn(ii) binding that triggers the closing of the hydrophobic gate. The gated water access to the transport site enables a stationary proton gradient to facilitate the conversion of zinc-binding energy to the kinetic power stroke of a vectorial zinc transport. The kinetic details provide energetic insights into a proton-coupled active-transport reaction.

Original languageEnglish (US)
Pages (from-to)101-104
Number of pages4
JournalNature
Volume512
Issue number1
DOIs
StatePublished - Jan 1 2014

ASJC Scopus subject areas

  • General

Fingerprint Dive into the research topics of 'Visualizing the kinetic power stroke that drives proton-coupled zinc(ii) transport'. Together they form a unique fingerprint.

  • Cite this